The objective of this proposal is to test the hypothesis that the expression of the active metalloproteinase matrilysin in human gastrointestinal tumors is causally involved in the progression of these tumors to an invasive and metastatic state. This hypothesis is based on the applicant's observations that 80% of human gastric carcinomas and 75% of human colon carcinomas tested expressed matrilysin mRNA, while no expression was detected in adjacent, grossly normal tissue. Matrilysin, a member of the matrix metalloproteinase family, degrades extracellular matrix components such as laminin and fibronectin, and there is an extensive literature correlating various members of this family to tumor invasion and metastasis. To test this hypothesis, the applicant proposes to modulate the level of matrilysin expression in human colon cancer derived cell lines using molecular genetic techniques to determine the effect of matrilysin on tumor cell invasion in vitro. In addition, the effect of matrilysin on invasion and metastasis will also be assessed in vivo using orthotopic cecum injection into athymic mice. Further in vivo testing of the effect of matrilysin on tumor progression will be carried out using a transgenic mouse model system in which activated matrilysin is specifically expressed in the colon. Tumors will be induced by chemical treatment and the effects on tumor progression form benign to malignant, invasive, and metastatic phenotypes will be assessed. In addition, experiments are proposed to better understand the molecular mechanisms underlying the induction of matrilysin gene expression in colorectal tumor progression. Primary human polyps will be examined by in situ hybridization and immunohistochemistry to determine the stage of colorectal tumor progression associated with the induction of the matrilysin gene and the population of cells expressing it.In addition, it is proposed to analyze the promoter region of the matrilysin gene for cis- and trans- acting transcriptional control regions for insights into possible signals that could induce this gene. These studies, combined with the current understanding of some of the genetic events that are involved in colorectal tumor progression, may provide insights into events that lead to the expression of a gene whose protein product then contributes to further progression to invasive and metastatic states. This combination of molecular, cell biological, and in vivo studies could eventually result in improved diagnostic and therapeutic approaches to the management of human gastrointestinal cancers.